Environment mapping controls missing in Texture context tab - Blender 2.8
The environment map can be set in the World tab or alternatively by using nodes in the Shader Editor.

To setup the environment map as depicted below, perform the following steps in the World tab on the default world configuration which only consists of a Background node connected to the World Output.


Click on the circular button for Color and select Environment Texture from the dropdown
Click on Vector and select Mapping
Click on the circular button behind Vector in Mapping and select Generated